The decorative lamp string innovates from C-type lamp string to peppertype lamp string, and from bare lamp string to pattern frame type lamp string. The pattern frame type lamp strings currently available in the market have many different types, but basically the pattren frame is a strip type provided with a plurality of fixed positioning members. The positioning member forms two fastening jaws entended upwardly from the pattern frame for holding a lamp socket. Since the positioning members and the pattern frame are integrally moulded with plastics, the decorative effect is therefore fixed without varieties.